1. Technical Field
The present invention relates to charge pumps, and more specifically, to a charge pump that has its sinking and sourcing currents proportional to the phase difference between its two inputs.
2. Related Art
In general, a conventional charge pump has two inputs and one output. The conventional charge pump is configured such that when its two inputs are out of phase, there is either a sinking current (flowing into the charge pump) or a sourcing current (flowing out of the charge pump) through its output. However, these sinking and sourcing currents in the conventional charge pump do not depend on whether the phase difference between its two inputs is large or small. Assume that the conventional charge pump is electrically coupled to a VCO (Voltage-Controlled Oscillator). It may occur that even when the phase difference between the two inputs of the conventional charge pump is small, the VCO is driven hard causing more jitters in the system.
It is therefore advantageous to implement a charge pump that overcomes the above described problems.